What is "standard military doctrine" for magic in Scarterra

Buff spells are the most important consideration

    Lets say that it takes two or three soldiers to equal one soldier of the tier above them. Maybe, if you care more about victory than the lives of your soldiers, you might be willing to deploy your weakest soldiers as arrow catchers to absorb casualties in place of more valuable soldiers in order to achieve victory.     Morality aside, magic in Scarterran means that expendable soldiers sent out as arrow catchers will die much faster than their real world medieval equivalents would die. So this tactic is a lot less popular, even among generals that don't care about their soldiers' well being.   The plurality Scarterra's battlefield applicable magic fall under the category of a "buff spell". There are too many spells to list them all here individuals but various buff spells can make soldiers stronger, faster, tougher, or even improve their accuracy and reaction time. Spells can also achieve the same effect by improving soldiers' weapons and armor.   Buff spells will let a soldier effectively hop up a tier, or with multiple buff spells, they can hop up two tiers.   Buff spells make any soldier stronger, but they are most powerful when cast on a soldier who is already quite skilled. Past the "hero" tier you functionally unlock the "demigod" tier. Demigods are capable of chopping down lesser foes like wheat.   Standard military doctrine is to take your very best warriors, give them as many magical enchantments as you can, and put them up front.   Spell-casters go immediately behind your best warriors. The other side is going to doubtlessly target your spell-casters, so you embed them in units with your second best warriors acting as body guards. That way if a small probing force from the other side breaks briefly makes it past the front lines, that small force isn't able to slaughter the other sides mages and theurgists with impunity. A full breach is necessary in order to seriously target the other sides' spell-casters.   In most cases, the third best warriors stay back as reserves. They wouldn't stand a chance against elite enemy units with proper buff spells, but if you neutralize the other side's spell-casters, in any section of the battlefield, the other side will probably falter and you can use your reserves to exploit the opening. Or if your side breaks, your reserves can cover the retreat. At that point, it becomes more strategically viable to sacrifice your weakest troops for the greatest good.   If a general is fortunate enough to have access to LOTS of spell-casters, standard military doctrine is to put the best near the front and keep the secondary casters with the reserves. Then, when the first wave of spell-casters run low on mana and/or quintessence, they can switch places with the reserve casters. That way the army can keep the flow of fresh spells going on longer. Even if your side doesn't kill the other sides' casters, your side can win if your magic can outlast the others in a battle of attrition...and relatively bloodlessly too because in this case the losing side will probably withdraw.  

"Hex" Spells

  "Hex" spells are spells that make people weaker, slower, or clumsier. "Buff" spells will send up a soldier up a tier or two, and "Hex" spells will knock a soldier down a tier or two. In theory, hex spells should be just as commonly seen as buff spells, but they are not.     Enemy spell-casters are always priority targets, but soldiers hate hexes and the people who cast them, so these casters are targeted with extreme prejudice. At the end of a battle, the victorious side often "accidentally" fails to notice when the enemy hexers are actually trying to surrender. Conversely, captured spell-casters of buff spells are usually treated with dignity, and they may be offered a chance to switch sides.   That doesn't mean hexes are never used on the battlefield. But it does mean that hexers either have to be very loyal or very well-paid. When used, they are typically deployed in second line with the buff casters. This also makes them harder for the enemy to specifically identify.    

Magical healing

  A small amount of magical healing will keep soldiers from bleeding to death in a ditch, so they can eventually make a full recovery and live to fight another day. Just knowing that this healing is available will spur soldiers to fight harder and take more risks.   More powerful magical healing will let a soldier go from death's door, to being fully back in fight. Just like with standard "buff" spells, powerful magical healing is most effective when it is prioritized on stronger soldiers.   Honorable war doctrine states that enemy healers should not be individually targeted and they should be given full quarter. Pragmatic military doctrine states that enemy healers should be eliminated as quickly as possible.  

Mobility Spells

  The most important mobility spells on a Scarterran battlefield are usually spells that bestow flight. But spells can help with stealth or speed also qualify as mobility spells.   If a general has mobility spells at his command, standard offensive military doctrine is to take your strongest soldiers, buff them as much as them as possible, and then have try to either have them eliminate the enemy officers or to eliminate the enemy spell-casters.   Standard defensive military doctrine is to keep a reserve of elite soldiers armed with mobility spells to fly towards areas of the battlefield facing unexpected resistance. Often this results in flying offensive soldiers being opposed by flying defensive soldiers in a medieval fantasy dogfight.   If you are a soldier and get defeated in an arial battle, hopefully you are flying over your sides' troops rather than flying over enemy troops. Landing or crashing into a mass of enemy soldiers is not an ideal scenario.  

Damaging Spells

  Damaging spells just try to wound or kill the enemy as quickly as possible, never mind buffing or hexing anyone. These primarily but not exclusively part of Invocation for mages or Wrath for theurgists.     Mages and theurgists capable of direct damaging spells are often deployed with archers since they fill the same basic niche. Though a Scarterran with a longbow or crossbow can fire a lot farther than an invoker can, so generals have the high risk option to deploy their ranged magical support in the second or third line, though this makes these casters very tempting targets. They are almost as hated by the other side as hexers are.

An army marches on its stomach. Short-term, the most important military resource is food and water.   Long-term, the most important military resource reagents. Reagents allow for the creation of potions and advanced spells. Scarterran articles depend on reagents much how modern armies depend on petroleum.